A self mailer can have inserts inserted in them,
if the folding equipment has inserting capabilities. One or two inserts, depending
on equipment capabilities, can be inserted after the first fold is made. After
the inserting, the second fold is made and the mailer is sealed. Generally all
edges are sealed so the inserts are secure in the mailer. Be sure the inserts
are not too large that they interfere with the sealing process.